Air conditioning system



Aug. 16, 1955 w. s. STAl-R AIR CONDITIONING SYSTEM 2 Sheets-Sheet 2Filed Sept. 10 1951 FAN MOTO R.

3m 5. w m m M K M 0 K mo Rm PM M m 3 5 (Ittorncgs United States Patent 0Am CONDITIONING SYSTEM William S. Stair, York, Pa., assignor to YorkCorporation, York, Pa., a corporation of Delaware Application September10, 1951, Serial No. 245,894

3 Claims. (Cl. 257-3) This invention relates to a heating and coolinginstallation for ofiice buildings, hotels, apartment houses and thelike.

Specifically, it concerns an installation which comprises a centralcirculating system for a liquid heat exchange medium. A central heaterand a central cooler are provided whereby said medium may be selectivelyheated or cooled. The liquid passes through the liquid paths of aplurality of heat exchangers. One of these heat exchangers is includedin each of a plurality of individual room units. These room unitsinclude reversible refrigerating apparatus.

This refrigerating apparatus includes a motor driven compressor, theabove heat exchanger and a second heat exchanger, the first and secondheat exchangers being connected to function interchangeably as acondenser and as an evaporator. Each of the room units also includes afan whereby room air or a mixture of room air and fresh air iscirculated in heat exchange relation with the second heat exchanger.Depending upon the manner in which the compressor and the two heatexchangers are connected, the units may operate to absorb heat from thecirculated air and reject it to the circulated medium or they may absorbheat from the circulated medium and supply it to the circulated air.

During the summer the room units will be operating to absorb heat fromthe air. Under this condition, the central cooler is operated so thatthe medium is at a reduced temperature when it reaches the room units.

In the winter the room units are reversely conditioned so that heat isdelivered to the circulated air. Under these conditions the heater isoperated so that the circulated medium is supplied to the units at anelevated temperature.

Between seasons the load on the system may be unbalanced. Under theseconditions the individual room units may act either to heat or to coolthe circulated air, and the operation of each unit is independent of theoperation of the other units throughout the building. During this timeof the year, the circulated medium is supplied to room units at the sametemperature as during the heating season.

The elevated temperature to which the medium is raised during theheating season and between seasons is not so high as would precludeoperation of the room units as coolers. The safe operation of the unitsas coolers depends upon the condensers being adequately cooled by thecirculated medium. The units are so designed as to capacity that theymay be operated as coolers when the temperature of the circulated mediumis equal to or less than the elevated temperature. This feature insuressafe operation during the between seasons period of the year. A safetyswitch is provided to prevent operation of the compressor should thetemperature of the circulated medium become excessive. Because theelevated temperature to which the circulated medium is raised during theheating season and between seasons is not high, appreciable quantitiesof low-level waste heat 2,715,514 Patented Aug. 16, 1955 from laundries,kitchens and similar sources in hotels, and apartment houses can beapplied to the circulated medium to maximum advantage.

A system built according to this invention provides a singleinstallation which is operable either to heat or to cool the building.It is also operable to heat or cool any particular room or rooms in thebuilding independently of its operation in other rooms.

It will be seen that the system combines a heating system and individualroom air conditioning units in a manner which alfords an installationwhich is very flexible in its operation. It is not necessary that thepipes in the circulating system be insulated. The refrigeratingapparatus, when acting to heat the room, operates as a heat pump. Thisheat pump absorbs heat from the circulated medium which may berelatively cool and supplies heat to the room air at an elevatedtemperature. The heat absorbed from the circulated medium must besupplied from other sources such as gas, oil or coal. Hence, the systemis particularly adapted to localities where costs of these fuels arerelatively high and costs of electric power relatively low. Furtherreduction in normal electric power rates may be anticipated by virtue ofthe high annual load factor resulting from operation of the motor drivencompressors during the heating season and between seasons, as well asduring the summer for cooling only.

Figure 1 is a diagrammatic showing of a preferred embodiment of theinvention;

Figure 2 is a diagrammatic showing of one of the room units;

Figure 3 is a diagram of a typical control circuit for one of the roomunits.

The closed circulating system comprises an expansion tank 11 locatednear the roof 12 of the building. The tank 11 is provided with a floatcontrolled make-up connection 13 and a drain 14. Liquid passes from thetank 11 through the motor driven circulatory pump 15 through theconnection 16 to the heater 17. After passing through the heater 17, theliquid flows through a manifold 18 to risers 19 and to the room unitsgenerally indicated at 21. The room units are connected in parallelbetween the risers 19 and return lines 22 through which the heatexchange liquid flows to the collector 23 and the cooling tower 24located on the roof of the building. From the tower 24 the fluid returnsto the expansion tank 11. A by-pass 25 extends between the collector 23and the expansion tank 11. A manual valve 7 is interposed in the by-pass25; another, 8, in the steam supply line; and a third, 9, in the linefrom the collector 23 to the cooling tower.

Flow through the bypass 25 is controlled by a pneumatically operatedvalve 26, as will be more fully described. The supply of steam to theheater 17 is controlled by a pneumatically operated valve 27 which isthermostatically controlled. Direct fired heating means, using any typeof fuel, and a thermostatically actuated switch for its control may besubstituted for heater 17 and steam valve 27. Because the temperature ofthe circulated medium during the heating season is far below thatrequired in conventional hot water heating systems, maximum fuel economyis possible.

The thermostatic control system for the valves 26 and 27 includes threepneumatic thermostats 28, 29, and 31. The thermostat 28 has a branchline 32 connected to the thermostat 29. The branch line 33 of thethermostat 29 is connected to the pneumatic valve 27 and to the relayvalve 34. The thermostat 28 is responsive to outdoor temperature sensedby the bulb 35. Thermostat 29 is operated in response to the temperatureof the circulated medium leaving the heater 17. Thermostat 28 is areverse-acting instrument and serves to readjust the control point ofthe thermostat 29 so that value the relay valve is opened and vents thebranch line 36'of the thermostat 31. Thevalve 26 is ;open when the line36 is vented. When the pressure-in ;the branch line 33 -reaches thispredetermined value the valve 27 is opened. As long as the relay valve'34 is closed, the thermostat 31 controls the opening and closing of thevalve=26. The thermostat 31 is responsive to the temperature of thecirculated medium in-the tank 11 which is sensed by the bulb 37.

The thermostat 31 is active duringthe between seasons period-of theyearto maintain a constant temperature in the tank -'1- 1.' During'thecooling season the valve 26 will normally remain closed. 'Manual valve 7can be closed at :this time.

As shown in Figure '2, the room units "21 include a motor drivencompressor -38, a first heat exchanger '39, and a second heat exchanger41. A fan 42 draws air from the room air inlet 43 and the fresh airinlet 4,4 and circulates it in heat exchange relation with the firstheat exchanger 39. The proportion of fresh and room air circulated bythe fan ,42 is determined by the damper 45. This damper is manuallyoperated in the illustrated embodiment, 'but' could be operated by athermostatically controlled motor. Such .motors and their controls arewell 'known in the art;

The heat exchanger 39 is made in two sections, 39 and '39". When theheatexchanger39 is serving as a condenser, as will be more fully described,both sections 39' and 39 are effectively used as-heat exchange surfaces.During operation of this exchanger as an'evaporator the lower-section"39 carries the heat exchange load while upper section '39 serves only.as a part of the suction ,line through which vaporized refrigerant is returned to the compressor. This arrangement provides the added heatexchange surface which is required when the coil 39 is operated as anair cooled condenser.

"I he second heat exchanger 41 maybe of the double pipe type. The liquidheat exchange medium from the closed circulatory system flows throughthe inner pipe indicated in dotted lines, and refrigerant passes throughtheannular space; a

A valve 46 controls the direction of flow of refrigerant through theheatexchangers 39 and 4 1. In the positionillustrated, compressedrefrigerant vapors flow from the compressor discharge 47 to the heatexchanger 39 which isoperating as a condenser. Heat exchangerfll Visoperating as an evaporator. Valve 46 may be shifted so as to dischargecompressed refrigerant vapor totheiheat exchanger 41 while drawing gasfrom the exchanger 39 through the suction'line 48. The function of thetwo heat exchangers may thus be interchanged. Expansion of the liquidrefrigerant is controlled by a restrictor tube 49, although otherexpansion controlling means can he used.

7 ing control switches 54 and 55. The switch 53 is thermostaticallyoperated in response to room temperature and is effective to open thecircuit when the room temperature falls below a predetermined minimum.The

switch 54 is -,a thermostatically controlled switch and is eflfective toopen the circuit when the room temperature exceeds a predeterminedmaximum. Switch 55 responds to temperature .of the circulated liquidleaving the heater 1 7 and shuts offthe compressor when it exceeds apredetermined It is ,a .safety co ntrol.

Operation During the heating season valve 7 is opened and valve 9 may beclosed so that the by-pass 25 between the col-. lector 23 and the tank11 is open and the cooling tower 24 is idle. Valve 8 is opened and steamis supplied to the heater 17 so that the temperature of liquid suppliedto the system is elevated .to .the desired value. When the room units 21are arranged as shown in Figure 2, the heat exchanger 39 acts as acondenser and heat exchanger ,il .acts .as an evaporator. Thus .it willbe'seen that 'the unit acts as a heat pump to absorb heat from thecirculated medium and deliver it to the room air.

During -the summer, when cooling is desired, the valve 46 is moved tothe positionin which the heat exchanger 41 functions as a condenser andexchanger 39 functions as an evaporator. The switch 52 is positioned'sothat the summercontrols are operating. Valve 8 is closed and t ea e 1 isshu dhwh- T Y-Psss .2 m he hssd lh ihsr l 7- a Y s hu ed s as to causethe circulated medium to pass through the coolhe Q s 4- h rj om un t unl5 .,Ql1 i QP operate a a hhv fihg lh i h r s u h Wat c le shds s is idah -hs s :i rs ssd fli isn ma be realized. I V l i 7 i I .Bs wssh thsumme an win e so the lo d .0 the hs llatiq k h s h 1ahssd be a e for eam l lhhih h ths hQ th s swih he @9 w i those I the south are Warm. Theroom unitsean be independently stth s hrhs th @9 asth nc upa t hs eo lmy d sir hi t n is ssha lsd th s t n of the .-.D. .g t e h n is hsqh th fi er n ppar ms a 3 h??? P P.- .I' she hi bsor a a r lativ r. a shd l vns ata nc high r temperaturehs s rs hsni qu a ssim i m need uothsnppl'ed at as high a .te p

V T si s n un n latsd P n results ins ehs sra l av h i sta ation costs-What is claimed is: a 1. A heating and cooling installation forbuildings ompr sins hfiqm n tion, a cir ul t g system through which ,aheat exchange medium is circulated, the system including ,means tocirqulaterthemedium, a cooler operable to cool said medium, a heateroperable to {heat said medium, said heaterand cooler being selectivelyoperable,

and a supply riser and .a return riser; a plurality of independentlyoperable ;room ;units, .each unit including reversible refrigeratingapparatus, said apparatus including ,flifi TSI and second heat exchanger.operatively lDtCI". connected and interchangeablyefiectiverespectivelyas a pathzhavingjm sends directly connected .tosaid supply riser and to said return riser, means to circulate air.tobe.

suppliedato the. :room in heat exchange relation .with the othenheatexchangerin each unit; and means controlling the temperatureof. thecirculatedmedium supplied to the heatexchangersthrough whichcit flows,said temperature beingsuchthatthe liquid will serve as a source ofheatin thosev exchangers operating as a refrigerant evaporator but less.than themaximum permissible for it to -act as a cool- 7 ing medium inthoseheat exchangers which areoperating as refrigerant. condensers.

2. The method of conditioning airin a building which consistsincirculating a-liquid heat exchange medium to a plurality of heatexchangers, connectedinparallelflowrelation, andlselectively .andindividually operating said heat exchangers as the heat absorbing orheat'dissipating' eratnreas is characteristic of 7 t when t the maximumis less than the maximum permissible for cooling any of the heatdissipating surfaces which it contacts and circulating air in heatexchange relation with the other heat exchange surfaces of said units.

3. A heating and cooling installation for buildings comprising incombination, a circulating system through which a heat exchange mediumis circulated, the system including means to circulate the medium, acooler operable to cool said medium, a heater operable to heat saidmedium, said heater and cooler being selectively operable, and a supplyheader and a plurality of supply risers connected in parallel flowrelation therewith and a return header and a plurality of return risersconnected in parallel flow relation therewith; a plurality ofindependently operable room units, each unit including reversiblerefrigerating apparatus, said apparatus including a first and secondheat exchanger operatively interconnected and interchangeably efiectiverespectively as a refrigerant evaporator and as a refrigerant condenseror respectively as a refrigerant condenser and refrigerant evaporator,one of said heat exchangers in each unit having a path for circulatedheat exchange medium, said path having its ends directly connected toone of the aforesaid supply risers and to one of the aforesaid returnrisers, means to circulate air to be supplied to the room in heatexchange relation with the other heat exchanger in each unit; and meanscontrolling the temperature of the circulated medium supplied to theheat exchangers through which it flows, said temperature being such thatthe liquid will serve as a source of heat in those exchangers operatingas a refrigerant evaporator but less than the maximum permissible for itto act as a cooling medium in those heat exchangers which are operatingas refrigerant condensers.

References Cited in the file of this patent UNITED STATES PATENTS Re.22,100 Brace et al. May 26, 1942 2,260,887 Dasher Oct. 28, 19412,401,890 Smith et al. June 11, 1946 2,441,885 Kemler et al. May 18,1948 2,513,373 Sporn et al July 4, 1950

